Underground conduit construction



June 4, 1935. M. CRAIGHEAD UNDERGROUND CONDUIT CONSTRUCTION Filed March 50, 1933 2 Sheets-Sheet l RM m flmN N n W Enw O W 3 r @A C Q U 4. dYM u B mu m a GI June 4, 1935. M. CRAIGHEAD 2,003,580

UNDERGROUND comm CONSTRUCTION Filed March so, 1955 2 SheetsSh et 2 I INVENTOR X M cmwghiaal BY 'P L wle Bea KF wmm ATTORNEY5 Patented June 4, 1935 u UNITED STATES PATENT OFFICE UNDERGROUND CONDUIT CONSTRUCTION Magruder (lraighead Greenburgh, N. Y. Application March 30, 1933, Serial No. 663,569 4 Claims. (Cl. 13'775) 'I'his invention relates to underground conduit I provide for the thrust of these supports and constructions of the type used for enclosing steam take care of the flanges or bells of the conduit pipes and the like. Ordinarily such conduit sysproper by a single expedient; this consists in terns include a bottom tile or underdrain to take providing support-members between the conduit '5 away water collections, and above this is posiandthe underdrain which will hold the conduit 5' tioned the conduit proper. Such conduit ordiabove the underdrain far enough so that the narily is made of vitreous ware (though somebells clear theunderdrain, and so arrange these times made of metal) with bell and spigot consupport members that they are held positioned nections, but instead of being made in the form directly in line with the thrust of the-internal of full circular pipes, ordinarily is installed as roll frames. In this way the Weight of the Steam 10 half sections. The steam pipes are positioned pipes is transmitted through the conduit walls in the conduit sections, and in order to hold without exerting any undue strain on these walls them in proper place, a support ordinarily called and Without the necessity of perforating them,

a roll frame, is used. As the steam pipes imso thatsubstantially I obtain the full strength pose a considerable load which would tend to of an external roll frame support but without its 15 break the vitreous conduit sections, it hasheretoece sa y and nherent drawbacks. fore been thought desirable in many instances so The support members which are positionedbeto arrange the pipe supports or roll frames that tween the underdrain and conduit shell may be they extend through the bottom of the conduit made as separate sectional units or they may and transmit the weight of the steam pipes to be formed integral with the conduit sections; as 20 some form of external support, which might be a third alternative, which is somewhat less dethe underdrain. In order to carry the roll frame sirable, they may be made integral with the unto the exterior, it follows as a matter of course derdrain sections. In any case, some means is that'the conduit sections must be perforated, provided such as notches or flanges on the co- 5 which is objectionable in that it tends to permit operating parts so that the support members will moisture to enter the conduit and also may act be heldin a proper predetermined-position and as a conductor of electric currents which may this position is so arranged that when the roll have an injurious effect on the steam pipes, parframes are put in place in the conduit sections, ticularly in the summer time when unused heatthe roll frames also will be held so that their ing lines are apt to become very damp and thrust is in line with the support members. electrolytic action may occur. Ordinarily where My invention can readily be understood by such external type of roll frame is used, the conreference to the accompanying drawings in which duit sections are perforated intermediate their Fig; 1 is a sectional View of a form of device'in ends and the external portion of the roll frame which the support members are made integral is brought down to rest on the underdrain at a with the lower conduit sections; Fig. 2 is a side 35 junction point between the sections of the under-- view with a part broken away showing the condrain. Since the conduit sections are now made struction of Fig. 1; Fig. 3 is a side view of one to rest directly on the underdrain, the latter section of conduit showing what occurs when the must be cut away to provide space forthe bell underdrain is not laid quite true. In Fig. 4 I

40 ends, and as these openings will come intermeshow a view. similar to Fig. .l (but with the roll diate the ends of the underdrain se'ction's,it' is frame and pipes omitted) but in this case the necessary that the underdrain tiles must either support members are separable from the conduit, be made and laid with great accuracy or (asis and also in this figure the conduit is shown as ordinarily the case) they must be laid sufiiciently made of metal. Fig. 5 is aside view of a construcfar apart so as to allow some longitudinal flexition shown in Fig. 4 with a part broken away to bility in positioning them relative to the bells. indicate that metal and vitreous conduit sections My invention relates to a system of this gencan readily be used in a. single system. Fig. 615' eral type which is of great strength and staa detailed sectional view showing a" difierent bility, which can be manufactured efficiently, shaped underdrain and support member from and can be installed quite simply and inexpenthatshown in Fig. 4. Fig. 7 is a section similar 50 sively while overcoming some of the difficulties to Fig. 4 showing the support members made of the types heretofore in use. In carrying out integral with the undertile, and Fig. .8 is'a side my invention, I do away with the use of external view of this construction. rollframe supports and keep these supports en- In Fig; 1 the underdrain I0 is formed with its tirely within the conduit, but at the same time sides converging toward the top l2, and'substantially directly above the sides are formed notches M which receive the support legs Hi. In this case these legs constitute the support member but are made integral with the lower conduit section [8. The roll frame 20 is provided with ribs 22 which are received by notches formed in the conduit section l8 opposite the legs l6. This roll frame is provided with stepped notches 24 to receive the axle bars 26 which are provided with rollers 28 to carry the steam pipes. The top half of the conduit is designated by the numeral 30 and these two halves may be held together in some appropriate way as for example by the clamps 32 and wedges 34, or simply may be held by the weight of the backfilled earth.

With this form of construction the underdrain l is first laid in place in the trench in the usual manner preferably with a fill ofbroken stone on each side. The underdrain is laid without regard to the longitudinal position where the conduit sections will come, but generally it is best roughly to position the underdrain so as to break joints with the conduit sections. The underdrain sections preferably are laid with their ends quite close together so that they can receive seepage but will not have large enough openings to endanger was-houts under the underdrain, resulting from large flow of water in the underdrain. As shown in Figs. 2 and 3, the support members or legs l6 extend along the conduit sections for less than their entire length, leaving ample room for the bell of one section to surround the spigot of another,- and for the joint to be properly packed with cement or a bituminous compound in the customary manner, by trowelling or by the use of a joint runner. These legs or support members are made of such depth that bells of the conduit sections are kept above the top [2 of the underdrain so that there will be no strain on the bell sections and it will not be necessary to cut away the top of the underdrain sections. If by chance a conduit section is misplaced relative to the underdrain and the legs [6 do not rest in the notches [4, the conduit section will tip over far enough to make this immediately apparent and the parts will immediately be positioned properly. This cooperation of the legs IS with the notches M ordinarily will keep the conduit sections properly aligned while the roll frames and steam pipes are being put in place and ordinarily it will not be necessary to cement these bottom sections together (as heretofore has been customary) in order to provide the necessary stability to permit the installation of the steam pipes without disturbance of the conduit. The roll frames are put in place in the conduit sections with the ribs 22 positioned in their appropriate notches 50 that the thrust of these supports runs directly through the sides of the conduit sections to the legs l6, thence through the sides of the underdrain It] to the ground. The steam pipes are.

installed in the usual manner with appropriate insulation which, as is understood in the art, may be either a direct insulation around the individual pipes as here indicated, or may be in the form of a filling for the conduit sections. If during the installation of the roll frames and steam pipes, any of the bottom conduit sections have become misplaced, this will be immediately apparent, as the'le gs I6 will either restin their'notches or the section will be tipped at a substantial angle so that the need of adjustment is seen. When the steam pipes are in place and the proper positioning 'of' the bottom conduit sections has been checked up, the cover members 30 are putv on and may be fastened down to the lower sections as by the clamps 32 and wedges 34. Any appropriate form of cement is placed between the halves of the conduit as is understood in the art. After the cover sections of the conduit are put in place, the bell and spigot joints between the sections can be closed each as an entire unit by the use of a joint runner which makes a far more eificient closure than cementing up the bottom halves as one operation and later sealing the top halves. Actually, experience shows that where the bottom halves of the conduit sections are cemented together before the steam pipes are installed, there is a serious danger of these joints being broken during installation operations and such breaks may not be discovered. On the other hand, Where sealing of the joints is done as a final operation, there is very little danger of the joints being broken.

With the form of construction here described, it will be seen that the weight of the steam pipes is transmitted in such a way that no strain is exerted on the conduit shell tending to break the same and that if for any reason any of the parts have been misplaced, this will be immediately apparent so that the same can be rectified before the installation is complete. At the same time, the necessity of perforating the conduit is done away with and the whole conduit can be sealed tightly against moisture, and the vitreous sections will act as an insulator to eliminate electrical action which (as stated above) may occur where metallic roll frames are carried through the conduit casing to the ground. In the form of device shown in Figs. 1, 2 and 3, the support legs l6 actually serve to strengthen the conduit. sections and eliminate localized pressure that might result where the underdrains are at angle relative to each other. This is shown in Fig. 3 where the underdrain sections H) are indicated at an exaggerated angle. In this case supports or legs [6 will contact with the underdrain at their ends, but due to their shape these supports will have adequate strength to distribute the strains throughout substantially the entire length of the corresponding conduit section.

In Fig. 4 the undredrain I0 is similar to the underdrain III of Fig. 1 but in this case aseparate member I3 is provided having legs 15 and notches I! which receive corresponding projections formed in the bottom conduit section l9. In this case the conduit section is shown as made of metal, but'it may also, of course, be made of vitreous material as in the other figures. Where metal and vitreous conduit sections are to be used together (as indicated in Fig. 5) it is advis able that the internal diameters of the two he kept constant. The variation of the external diameter can readily be taken care of by the length of legs 15.

In Fig. 6, the underdrain I I is similar to under-- drain II) but is rectangular in cross section so thatordinary flue lining may be used. ,In this case the support member 2| is provided with flanges 23 extending over the sides of the underdrain.

Fig. 7 illustrates a case where the support members 25 are made integral with the underdrain 21 and the bottom half of the conduit 29 is provided with projections 3| to align with the support members. 25. In this case they are shown as coming outside of the support members though obviously they may be made to come between the support members, and in such instance only one broad projection is necessary. In any event,

these should be so positioned that the notches for the roll frames will come opposite the support members. This form of construction has many of the advantages of the preferred forms of Figs. 1 and 4 but has the drawback that the underdrain sections must be positioned accurately to receive the bells of the conduits as illustrated in Fig. 8. It is preferable to have the bells of the conduit come intermediate the ends of the underdrain tiles and so the support members are cut away to receive the bells as shown at 33. It will be noted that in any event the support members 25 preferably are high enough to keep the bells above the underdrain proper so that no perforation of the upper wall of the underdrain is needed.

In all of the forms described, it will be noted that means is supplied to create a direct thrust from the conduit sections through the support members and sides of the underdrain to the ground, and the notches or other means used to position the roll frame supports are so located on the inside of the conduit sections that the weight of the steam pipes is transmitted to and carried by this column-like arrangement. Since the various sections of underdrain, supports and conduit ordinarily will be made from uniform sets of extrusion dies, or molds, it follows that if the underdrain sections are laid in proper alignment, the conduit sections will all be aligned both angularly and vertically, with the result that when the roll frames are inserted in the places provided for them, they also will be properly aligned.

While I have shown a number of modifications of my invention, it is to be understood that these are given only by way of illustration and further forms and embodiments may be used without departing from the spirit of my invention.

What I claim is:

1. A series of conduit sections, a series of underdrain sections, roll frame supports adapted to fit inside the conduit sections, support members adapted to support the conduit sections upon and over the underdrain sections, and means carried by the conduit sections for positioning and carrying the roll frame supports in predetermined angular relation relative to the conduit sections so that their pressure is exerted substantially in line with said support members and is thereby transmitted substantially directly to the underdrain sections.

2. In a conduit construction, a series of underdrain sections, a series of support members separable from and resting on said underdrain sections, a conduit comprising top sections, and a series of approximately semi-circular lower sections carried by said support members and so connected with said support members that said conduit sections are located in predetermined angular relation to said underdrain sections, a series of roll frames fitting within said conduit sections, and means whereby said roll frames are held in predetermined angular relation relative to said conduit sections and thereby are held in predetermined angular relation relative to said underdrain sections.

3. A construction as specified in claim 2, in which the conduit sections are made with bell and spigot connections and in which the support members are made integral with the conduit sections and are of sufl'icient depth to support the conduit sections with their bells above the underdrain sections.

4. A construction as specified in claim 2, in which the lower conduit sections are provided with internal grooves to receive and position the roll frames and with external ridges substantially opposite said grooves to position said conduit sections relative to said underdrain sections.

MAGRUDER CRAIGHEAD. 

